Previous Experience and Reproductive Investment of Female Columbian Ground Squirrels
نویسندگان
چکیده
Reproductive success of females in iteroparous species usually increases early in life, then remains constant or declines. The restraint hypothesis suggests that primiparous females limit their 1st reproduction in order to avoid future costs to survival, reproduction, or both, whereas constraint indicates that primiparous females are limited in their 1st reproductive attempt either because they lack sufficient resources (measured by body mass) or lack experience at weaning a litter. To evaluate these alternatives, we examined ageand experience-related patterns of reproduction in female Columbian ground squirrels (Spermophilus columbianus) with data from a long-term study and by experimentally altering age at 1st reproduction. In the results of the long-term study, experienced females had significantly higher reproductive investment and reproductive success (number of offspring surviving to yearling age) compared to inexperienced females. Annual survival of females was not affected by their level of previous weaning experience or current reproductive investment. Additionally, subsequent reproductive success was not impaired by earlier reproduction. In the experimental results, experienced females had significantly higher reproductive investments compared to inexperienced females. Constraint in terms of previous weaning experience best explained the differences in reproductive investment and reproductive success between primiparous and multiparous females.
منابع مشابه
Senescence and age-related reproduction of female Columbian ground squirrels
1. Three hypotheses have been proposed to explain age-structured patterns of reproductive investment and somatic investment: residual reproductive value, senescence and evolutionary restraint. We evaluated these hypotheses for female Columbian ground squirrels ( Spermophilus columbianus ) by examining age-related patterns of somatic and reproductive investment. Females were designated as succes...
متن کاملSomatic senescence: evidence from female Richardson’s ground squirrels
We studied reproductive and somatic investments in /700 female Richardson’s ground squirrels (Spermophilus richardsonii ) of known age over a 14-year period to evaluate three hypotheses, restraint, senescence, and residual reproductive value, proposed to explain age-specific life history patterns in iteroparous vertebrates. We found that reproductive investment, measured as litter mass at first...
متن کاملKin selection in Columbian ground squirrels (Urocitellus columbianus): littermate kin provide individual fitness benefits.
Since W. D. Hamilton's seminal work on the evolution of sociality, a large body of research has accumulated on how kin selection might explain the evolution of cooperation in many group-living species. Our study examined the evolutionary basis of philopatry and cooperation; specifically, whether individuals benefit from the presence of close kin. We applied an individual fitness approach to a 1...
متن کاملAge-specific resource investment strategies: evidence from female Richardson’s ground squirrels (Spermophilus richardsonii )
To avoid a possible cost to their future survival and/or reproduction, individuals must balance their somatic and reproductive investments. The van Noordwijk and De Jong model of resource investment predicts that investments into reproduction and soma can vary among individuals of a population based on the variation in the total amount of energy that individuals acquire. With principal componen...
متن کامل